Retention devices, lattices and related systems and methods

ABSTRACT

A woven retention device that is configured to receive a fastener in a bone hole can be configured to promote bone ingrowth and impede biofilm formation. The woven retention device can be made of woven filaments that outline apertures of varying sizes and shapes and can serve as an interface between the fastener and the bone material. In a first relaxed state, the interwoven filaments can outline apertures of varying sizes and shapes within a predetermined range and in a second constricted state inside the bone hole with the fastener the interwoven filaments can outline apertures of decreased area that still fall within the predetermined range. The woven retention device can be configured to allow for optimal bone growth while at the same time minimizing the likelihood that biofilm forms thereon.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.62/432,399, filed Dec. 9, 2016, the contents of which is herebyincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to devices, systems and methods for use infixing fasteners to bone tissue. Specifically, the present inventionrelates to maintaining a pore size within a predetermined rangeregardless of the diameter of the device.

BACKGROUND

In orthopedic surgery it is common to secure a bone screw to a patient'sbone. Bone fracture repair is surgery to fix a broken bone using plates,nails, screws, or pins. It is common in the treatment of fractures toattach a plate to the bone utilizing bone screws. The resultingconstruct prevents motion of the fractured bone so that the bone canheal. Alternatively, one or more screws may be inserted across the breakto hold it in place.

In the treatment of spinal disorders, pedicle screws are inserted intothe patient's vertebrae to serve as anchor points that can then beconnected with a rod. This construct prevents motion of the vertebralsegments that are to be fused.

In the treatment of detached tendons, screw-like tissue anchors areinserted into the patient's bone to serve as an anchor for thereattachment of the tendon.

One complication with the use of bone screws is the loss of fixation orgrip between the bone screw and the patient's bone. Another complicationwith the use of bone screws is the stripping of the hole in the bonewhen the bone screw is inserted. This results in the loss of purchaseand holding strength of the bone screw.

The presence of osteoporotic bone or other disease states that weakenbone can increase the likelihood of complications by reducing thepurchase or grip of the bone screw to the patient's bone, resulting in aloss of holding strength and loosening of the bone screw or pullout ofthe bone screw.

Infections deep inside bone require systemic antibacterial treatments,which disrupt entire systems.

Cellular responses and micro-organisms that create biofilms and thegrowth of soft tissues prevent bony ingrowth. Materials and conditionsconducive for bony ingrowth may prevent the proliferation of biofilms orsoft tissue in place of bone where bone is preferred for fixation andstability. Such conditions may include the space for ingrowth as bonecells perform some space, but not an infinite amount of space. Thisspace may be the linear distance in 3-dimensions between obstructions.

A woven patch can be used in orthopedics. Currently, commercialapplications use mesh, for example, to secure the lower, tibial end of asoft tissue ACL graft. In this sleeve, as described in the GTS Sleevedocument, two of the lumens hold graft tissue and the third lumenaccepts the GTS tapered fixation screw. See GTS Sleeve document. Anothercommercial application, such as the Opti-mesh™ 3-D deployable mesh pouch(Spineology, Inc.), is used in the vertebral body by containing bonematerial and restoring the height of vertebrae. There are other fiber orsuture-based technologies that are not woven but function as a patch orshield. For example, pedicle shields have also been used with asemi-circular surface that are implanted within the pedicle to protectthe spinal canal.

There remains a need for solutions to secure bone screws and facilitatebone healing through woven devices, materials and/or patches.

SUMMARY

A woven retention device to promote bone ingrowth and impede biofilmformation can include a sleeve body comprising a plurality of interwovenfilaments; a proximal end that is proximal to the sleeve body and thatis configured to receive a fastener; and a distal end that is distal tothe sleeve body on an opposing side of the proximal end, wherein in arelaxed state of the woven retention device, the interwoven filamentsoutline pores, each of the pores having a pore size along a plane of thetubular lattice, each pore size within a range of 200-1000 μm, whereinin a constricted state of the woven retention device, the pore sizechanges as a function of a diameter of the sleeve body, the pore sizeremaining within the range of 200-1000 μm, and wherein the pores areconfigured to promote bone ingrowth.

An area of the pores can change dynamically by interwoven filamentstranslating with respect to each other without substantial deforming ofthe interwoven filaments.

The area of the pores can change by a function of a braid of thefilaments.

The pore size can be defined along a long axis or a major axis of thesleeve body.

The interwoven filaments can define a plurality of protuberancesdistributed on an interior surface and an exterior surface of thetubular lattice at a predetermined spatial relationship.

In the relaxed state each pore can be shaped as one of a diamond, arectangle, a square, or a parallelogram.

A woven retention device to promote bone growth can include a sleevebody comprising a plurality of interwoven filaments that form asubstantially tubular lattice having a plurality of pores having apredetermined pore size, the plurality of pores defined by a pluralityof adjacent filaments of the plurality of interwoven filaments, whereinthe woven retention device is configured to move between a relaxed stateand a constricted state, wherein the pore size falls within apredetermined range and remains substantially within the predeterminedrange when the woven retention device is in the relaxed state and theconstricted state, and wherein the pore size promotes bone growth in thepores.

The pore size can be defined by a 3-dimensional distance betweensurfaces of the plurality of adjacent filaments.

The pores can define a parallelepiped between the plurality of adjacentfilaments.

The 3-dimensional distance between surfaces of the plurality of adjacentfilaments is a length between opposing diagonal corners of the pores.

The pore size can be within the range of 200 μm and 1000 μm.

The pore size can be about 600 μm.

The pore size can be defined when the woven retention device is in therelaxed state.

A plurality of protuberances can be distributed on an interior surfaceand an exterior surface of the tubular lattice at a predeterminedspatial relationship.

The pore size can be defined along a long axis or a major axis of thesleeve body.

The pore size can remain in the range of 200 μm and 1000 μm when adiameter of the sleeve body changes.

A kit can include a first woven retention device having a firstdiameter, the first woven retention device having a first sleeve bodycomprising a first plurality of interwoven filaments that form asubstantially tubular lattice having a plurality of first pores; and asecond woven retention device having a second diameter, the second wovenretention device having a second sleeve body comprising a secondplurality of interwoven filaments that form a substantially tubularlattice having a plurality of second pores, wherein the second diameteris greater than the first diameter, and wherein the first pores and thesecond pores have substantially the same pore size, and wherein the poresize is within the range of 200 μm and 1000 μm.

The woven retention device can be configured to move between a relaxedstate and a constricted state, and wherein the pore size remainssubstantially within the range when the woven retention device is in therelaxed state and the constricted state.

The kit can include a third woven retention device having a thirddiameter, the third woven retention device having a third sleeve bodycomprising a third plurality of interwoven filaments that form asubstantially tubular lattice having a plurality of third pores,wherein, the third diameter is greater than the second diameter, andwherein a pore size of the third pores is substantially the same as thepore size of the first pores and the pore size of the second pores.

The first pores, the second pores, and the third pores can be defined bya 3-dimensional distance between surfaces of adjacent interwovenfilaments of the respective plurality of interwoven filaments.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A shows a perspective view of a screw, an implantable retentiondevice and a bone, according to an embodiment of the present invention.

FIG. 1B shows a screw and an implantable retention device fixed inside abone hole, according to an embodiment of the present invention.

FIG. 1C shows a perspective view of a screw, a woven patch and a bone,according to an embodiment of the present invention.

FIG. 2 shows an implantable retention device with a tapered end alongits longitudinal axis, according to an embodiment of the presentinvention.

FIG. 3 shows a close-up view of a portion of the implantable retentiondevice shown in FIG. 2 .

FIG. 4 shows a flow diagram of a method of utilizing an implantableretention device in an embodiment, in accordance with the principles ofthe present invention.

FIG. 5 shows a pullout strength comparison for a screw, a screw in astripped bone hole, and a woven retention device with screw in astripped bone hole, according to an example of an embodiment of thepresent invention.

FIG. 6 shows a pullout force versus hole diameter for a screw and ascrew with a woven retention device, in accordance with the principlesof the present invention.

FIG. 7 shows another pullout force versus hole diameter for a screw anda screw with a woven retention device, in accordance with the principlesof the present invention.

FIG. 8 shows another pullout force versus hole diameter for a screw anda screw with a woven retention device, in accordance with the principlesof the present invention.

FIG. 9 shows pullout forces measured for woven retention devices ofvarying construction pulled from a first material, according to examplesof embodiments of the present invention.

FIG. 10 shows pullout forces measured for woven retention devices ofvarying construction pulled from a second material, according toexamples of embodiments of the present invention.

FIG. 11 shows an exemplary pore shape of a woven retention device,according to embodiments of the present invention.

FIG. 12 a shows a small diameter woven retention device, according toembodiments of the present invention.

FIG. 12 b shows a medium diameter woven retention device, according toembodiments of the present invention.

FIG. 12 c shows a large diameter woven retention device, according toembodiments of the present invention.

FIG. 13 shows a schematic of a woven retention device, according to anembodiment of the present invention.

FIG. 14 shows an exemplary bone growth in a study, according toembodiments of the present invention.

Additional features, advantages, and embodiments of the invention areset forth or apparent from consideration of the following detaileddescription, drawings and claims. Moreover, it is to be understood thatboth the foregoing summary of the invention and the following detaileddescription are exemplary and intended to provide further explanationwithout limiting the scope of the invention as claimed.

DETAILED DESCRIPTION

Some embodiments of the current invention are discussed in detail below.In describing embodiments, specific terminology is employed for the sakeof clarity. However, the invention is not intended to be limited to thespecific terminology so selected. A person skilled in the relevant artwill recognize that other equivalent components can be employed andother methods developed without departing from the broad concepts of thecurrent invention. All references cited anywhere in this specification,including the Background and Detailed Description sections, areincorporated by reference as if each had been individually incorporated.

The devices, systems and methods described herein may be used in thearea of orthopedics and, in particular, orthopedic repairs. Theseinclude various devices, systems and methods directed to fixing and/orretaining fasteners in orthopedic applications. Fixing or retainingfasteners to bone tissue is complicated by the underlining bone tissue.Understanding that an underlying cause of failure with internal fixationin bone tissue is the bone, the devices, systems and methods describedherein provide for solutions that address the implant site. At theimplant site, the hole and the bone benefit from an enhanced interface.

The fixation and/or retention devices, systems and methods describedherein maximize fixation and/or retention in the bone tissue, including,osteoporotic bone, bone of a poor quality, and mechanically poor bone inaddition to healthy bone tissue. The fixation and/or retention devices,systems and methods described herein may be used with any type offixation including, any types of screws, pins or fasteners.

The devices, systems and methods described herein enhance theinteraction of a fastener, such as a bone anchor, to a bone hole toprovide enhanced fixation. Additionally, the devices, systems andmethods may repair the surface of the bone hole following damage to thebone hole as in the case of stripping of the hole in the bone when abone screw is over-tightened. Also, the devices, systems and methodsprovide for an enhanced bone hole surface for the reattachment oftendons in, for example, anterior/posterior cruciate ligament repairprocedures, rotator cuff repair procedures, etc. The devices enhance thesurface of a bone hole to enhance fixation of a bone anchor to bone andpermits bone ingrowth into its structure. The devices enhance theinteraction between the surface of a bone hole and the fixation device.The devices interdigitate with the bony structure and interact with thefixation device. The device alone, as a single device, enhances thesurface of a bone hole to enhance fixation of a bone anchor to bone andaccommodates variations in the diameter and depth of the bone hole. Thedevices, systems and methods can enhance fixation without requiring theuse of cement and/or adhesives.

The retention devices, lattices, fixation sleeves and/or patches,systems and methods described herein maximize fixation and/or retentionin the bone tissue, including, osteoporotic bone, bone of a poorquality, and mechanically poor bone in addition to healthy bone tissue.The fixation sleeve and/or patches, systems and methods described hereinmay be used with any type of fixation including, any types of screws,pins, or fasteners.

The devices, systems and methods described herein can support a bonestructure. In one embodiment, the devices, systems and methods canenhance the interaction of a bone anchor, such as a screw, a nail or abone dowel, to a bone hole to provide enhanced fixation. Additionally,the devices, systems and methods may repair the exterior or interiorsurface of the bone following damage to the bone as in the case ofstripping of the bone when a bone screw is over-tightened. Also, thedevices, systems and methods provide for an enhanced bone surface forthe reattachment of tendons in, for example, anterior/posterior cruciateligament repair procedures, rotator cuff repair procedures, etc. Thedevices can enhance the surface of a bone to enhance fixation of a boneanchor to bone and can permit bone ingrowth into its structure. Inanother embodiment, the bone ingrowth can be enhanced with a coating ofbiological additive that actively promotes bone growth. The devices canenhance the interaction between the surface of the bone and the fixationdevice. The devices can interdigitate with the bony structure andinteract with the fixation device. The device alone, as a single device,enhances the surface of a bone hole to enhance fixation of a bone anchorto bone and accommodates variations in the diameter and depth of thebone hole. In one embodiment, the devices, systems and methods canenhance fixation without requiring the use of cement and/or adhesives.In another embodiment, bone void filler such as cement can be applied tothe surface of the bone and the patch to provide a passive patch.

Reference to a woven retention device is meant to include an implantablewoven, braided, or knitted patch or implantable retention device such asa sleeve. The woven retention device is not intended to be removable.Various embodiments described are meant to be interchangeably used witheach other. Furthermore, the terms “aperture” and “pore” are usedinterchangeably. The terms “filament” and “fiber” are usedinterchangeably.

Referring now to the figures, FIGS. 1A and 1B show a woven retentiondevice 100 for interfacing with a bone surface 104, according to anexample of an embodiment. The retention device 100, as shown, may have ageneral configuration or construction in the form of a hollow tubularshape shown as a sleeve body 106 including a plurality of interwovenfilaments that may form a substantially tubular lattice. The generalconfiguration of the hollow tubular shape can be selected to accommodatea typical shape of a pilot hole in bone, for example. Variousconfigurations of the sleeve body 106 can be contemplated in accordancewith the principles of the invention. The woven retention device 100 canbe any of the woven retention devices of co-pending application Ser. No.15/359,021, 15/374,773 and 14/569,542, herein incorporated by reference.

The lattice may include a plurality of protuberances distributed on aninterior surface 110 and an exterior surface 108 of the lattice at apredetermined spatial relationship. Each of the plurality ofprotuberances may be formed by an intersection of filaments. Moreparticularly, each of the plurality of protuberances may be formed by anintersection point of two or more of the plurality of interwovenfilaments. The intersection can be referred to as a location and/orpoint. Additionally, the interwoven filaments may outline apertures thatallow for bone ingrowth. The woven retention device can also have aproximal end 114 that is proximal to the sleeve body 106 and that isconfigured to receive at least a portion of a fastener 102 such that thesleeve body 106 may surround at least a portion of the fastener 102 wheninserted therein. The woven retention device 100 can also have a distalend 116 that is distal to the sleeve body 106. In some embodiments, thedistal end 116 is formed to ease insertion of the woven retention device100 into the bone hole 101. For example, the distal end 116 in FIG. 1Ais tapered or fused closed. The lattice can be a tubular lattice.

Embodiments of the woven retention device include a woven retentiondevice to promote bone ingrowth or impede biofilm formation. The wovenretention device 100 can include a sleeve body 106 comprising aplurality of interwoven filaments that form a substantially tubularlattice with a plurality of protuberances distributed on an interiorsurface and an exterior surface of the tubular lattice at apredetermined spatial relationship. The woven retention device 100 caninclude a proximal end that is proximal to the sleeve body and that isconfigured to receive a fastener; and a distal end that is distal to thesleeve body on an opposing side as the proximal end.

As can be seen in FIG. 3 and as will be described in greater detail, thewoven retention device 1008 can be configured such that the intersectingsets of filaments 120, 122 form a plurality of differently shaped anddifferently sized apertures or pores 148. In one embodiment, as shown inFIG. 3 , the first inner 130 and outer filaments 132 of one set of firstfilaments 122 can be grouped closer to each other than the other sets122 of first filaments. Likewise, the second inner 126 and outerfilaments 128 of one set 120 of second filaments can be grouped closerto each other than the other sets of second filaments. When the two setsof filaments intersect, as shown in FIG. 3 , the area which is outlinedby the first and second plurality of sets of filaments is a plurality ofdifferently shaped and differently sized apertures 148.

The area of the apertures can change dynamically by the interwovenfilaments translating with respect to each other without substantialstretching or bending of the interwoven filaments. When the wovenretention device is in a constricted or expanded state, the apertureareas can change by a function of the braid of the filaments.

The area of the aperture can be in a number of various shapes. Forexample, as shown in FIG. 3 , the apertures 148 can be in asubstantially rectangular or square shape. However, other shapes such ascircles and ovals are contemplated. The rectangles or square can be ofvarying sizes. The size of the shape of the aperture can be measured bya height and/or width for a square, triangle or diamond shape, a longand/or short axis for a rectangle, a diameter for a circle, and a majorand/or minor axis for an oval. In a relaxed state of the woven retentiondevice, the interwoven filaments can outline apertures having an areaalong the plane of the tubular lattice. Each area can be defined by adistance between filaments within a range of 200-1000 μm long axis ormajor axis in the relaxed state.

In a constricted state of the woven retention device 1008, the area ofthe apertures change as a function of sheath diameter, but each area ofthe apertures can still fall within the range of 200-1000 μm to promoteoptimal bone growth. For example, an aperture 148 can be a rectanglehaving a height of 800 μm in the relaxed state and in a constrictedstate the aperture can be a rectangle having a height of 500 μm. Byhaving differently shaped and sized apertures, a more conduciveenvironment for contact with non-uniform bony surfaces can allow foringrowth of bone to occur. Additionally, improved interdigitation withthe bony structure can be achieved with a combination of the aperturesand protuberances.

For example, at a first diameter, the size of the apertures or pores maybe within a predetermined range (e.g. 200-1000 μm) and at a seconddiameter, the size of the apertures or pores may remain within thepredetermined range (e.g. 200-1000 μm). Additionally, in the firstdiameter, the size of the apertures or pores may be substantially thesame as in the second diameter. For example, in the first diameter, thepore size may be about 300 μm and in the second diameter, the pore sizemay be about 300 μm. For example, in the first diameter, the pore sizemay be about 300 μm and in the second diameter, the pore size may be anysize within the predetermined range (e.g. 200-1000 μm), or vice versa.The first diameter may be a diameter of a woven retention device in arelaxed state and the second diameter may be the diameter of the wovenretention device in a constricted state. The first diameter may be adiameter of a first woven retention device and the second diameter maybe a diameter of a second woven retention device, where the first wovenretention device and the second woven retention device are in the samestate (e.g. relaxed or constricted).

The spatial relationship of the protuberances of the woven retentiondevice can affect the formation of biofilms on the fastener and/or onwoven retention device. For example, micro-organisms may attach to thefastener and/or the woven retention device. After attachment, themicro-organisms can mature and clog the apertures of the woven retentiondevice. For example, the apertures of the woven retention device allowfor porosity that enable bone ingrowth to occur, which facilitateshealing. In embodiments of this invention, porosity and pore sizes ofthe woven retention device are associated with these and otherbiological responses. For example, very small pore sizes or aperturesmake the formation of biofilms easier. One of the first stages ofdevelopment can include 1) initial attachment of the microorganisms, and2) irreversible attachment (which can lead to buildup). Embodiments ofthe invention here relate to both phases of preventing initialattachment by the filaments being thin enough and of a material toresist attachment and also having the pore sizes be large enough toprevent irreversible attachment. Thus, larger pore sizes can preventbiofilm attachment. Further, pore sizes can be affected by the degree ofthe weave intersections. At a 45 degree braid angle, an optimal poresize relationship can be achieved. Thus, even if a biofilm attaches tothe filaments, by having large pore sizes, spreading or maturing of thebiofilm can be prevented or slowed. Also, other biological responsesbesides biofilm formation, such as fibrosis, can be prevented with boneingrowth which relates to the pore size of the woven retention device.

Further there may be some materials that prevent the cellular responseof biofilms from building up and maturing. In some embodiments, thewoven retention device 100 can include an orthopedic biomaterial thatimpedes or prevents biofilm attachment or maturation and/or thatstimulates or promotes bone growth. Biomaterials in orthopedics can bemade of biocompatible, biofunctional, non-toxic, machinable, moldable,extrudable, having tensile strength, yield strength, elastic modulus,corrosion and fatigue resistance, surface finish, creep, hardness. Forexample, the interwoven filaments can include biomaterials and thebiomaterials can be manufactured in fiber format. The woven or non-wovenstructures described above can be made of non-resorbable orbioabsorbable polymers, metals, biological products or ceramics. Bioresorbable polymer material can be used. For example, the sleevematerial can be bioabsorbable and dissolve for complete healing, reducedrisk of particulate debris, and have no removal complications as aresult. The bioabsorbable polymer can include at least one ofthermoplastic aliphatic polyester (PLA), polyglycolide (PGA),polylactide (PLLA) and resorbable polyamides. Alternatively, the sleevematerial does not degrade but stays as a structural support of the bone.A non-resorbable polymer material can be biologically suited for use inbone, such as PET (polyehthylene terephthalate), ultra high molecularweight polyethylene, polyether etherketone (PEEK), polyetherketoneketone (PEKK), polypropylene, polyamides, PTFE, calcium phosphateand variations of sutures. Additionally, the non-resorbable polymermaterial may be coated with biologically active osteoinductivematerials, such as hydroxyapatite (HA), bone morphogenic protein (BMP),demineralized bone matrix (DBM), and the like.

A hydrophilic biomaterial such as a metal can be hydrophilic and attractbone. In one embodiment, metals can also be used such as titanium,tantalum, nickel titanium (nitinol), platinum, cobalt chrome/cobaltchromium, or a blend of all the listed metals. For example, the metalscan include at least one of nickel-titanium (Ni—Ti) or nitinol,stainless steel, platinum, titanium, cobalt chrome, cobalt chromium, orany combination thereof. In an embodiment, the metal material can beroughened to create a roughness characteristic that attracts bone, orencourage bone to grow to it or group to it. In an embodiment, thebiomaterial such as a metal can have a radioactive property such thatthe biomaterial can be detected using electromagnetic radiation, such asX-rays. In one embodiment, the woven retention device can be made offibers of a bone-promoting biomaterial in combination with fibers of amaterial that does not promote bone growth. For example, the wovenretention device can be made of fibers of titanium, which promotes bonegrowth, as well as PEEK, which promotes bone growth less. Additionally,fibers of PEKK, which can promote bone growth, can be used incombination with titanium and PEEK. In one embodiment, the filaments caninclude porous fibers.

In an embodiment, the woven retention device can be constructed with aninterior surface having a tap of the metallic biomaterial that followsthe path of a fastener such as a screw. In such a configuration, thewoven retention device is self-tapped to receive an insert, and as thescrew follows the path, the woven retention device is configured toexpand. In one embodiment, the self-tapping can be produced through theweaving pattern of the fibers or through a mechanical inscribing processthat machines thread that matches to the material into which the wovenretention device is being inserted. For example, one metal fiber can beincluded among all other plastic fibers and based on the pitch of thescrew, the metal fiber can be designed to follow the tap of the screw.

Biological materials or biologics, such as silk, collagen, and cat gutsuture can be used. See Park and Lakes, “Biomaterials: An Introduction,”1992, Chapter 4 (Park), the content of which is hereby incorporated byreference herein in its entirety. The biological products can include atleast one of silk and collagen. Thus, the sleeve can be made of sheetfabric materials such as Silk or Felt that is not woven, but could becreated by using collagen. An interior surface could be configured tointerface with different structures besides a screw (clamp, smooth,roughened) to provide a strong connection as long as there are manypoints of contact to provide sufficient sheer strength and a monolithicstructure (that is, if one point fails, whole structure does not fail).

The woven retention device 100 can be inserted into a hole in a bone andinteract with both the bone and a screw. While the woven retentiondevice 100 can achieve an interference fit functionality by providingadditional interference in between the fastener and the bone, in someembodiments, the woven retention device can instead of and/or inaddition to function as a woven retention device in accordance with theconfigurations, functions and advantages that are discussed herein. Forexample, the woven retention device can have a dual interface between aradial screw surface on one side and multiple points of contact on abone surface on the other side. The dual interfaces on the retentiondevice are configured to be adapted to the bony structure on the outsideand the screw on the inside, as described herein in accordance with theprinciples of the invention. The woven retention device can beparticularly beneficial for osteoporotic or weakened bone that has morespace gaps than normal bone to allow additional points of contact forthe interface to contact.

FIG. 1A shows the woven retention device 100 in an exploded state withthe fastener 102 outside of the retention device, and both the fastener102 and the retention device 100 are outside of the bone hole. FIG. 1Bshows the fastener 102 inside the woven retention device 100, which isinside the bone. FIGS. 1A and 1B also illustrate an example of a porousinterior structure of the bone. However, embodiments of the inventionare not limited to being used with the exact porous structure shown, asthe structure and porosity of bone can vary. In addition, although thebone illustrated in FIGS. 1A and 1B resembles a human femur, embodimentsof the invention are not limited to a particular bone. An advantage ofsome embodiments of the invention is that a woven retention device canbe provided for use in a variety of bones and bones exhibiting varyinglevels of porosity.

Thus, a woven retention device 100 for interfacing with a bone surfacecan include a sleeve body 106 comprising a plurality of filamentsforming a substantially tubular lattice with a plurality ofprotuberances distributed on an interior surface and an exterior surfaceof the tubular lattice at a predetermined spatial relationship. Thesleeve body 106 can be configured to surround at least a portion of afastener 102. Each of the plurality of protuberances can be formed by anintersection point of two or more of the plurality of filaments thatoutline a plurality of apertures. The sleeve body 106 can include anorthopedic biomaterial

The woven retention device 100 can include a proximal end 114 that isproximal to the sleeve body and that is configured to receive at least aportion of the fastener 102. The woven retention device 100 can includea distal end 116 that is distal to the sleeve body. In a first state,the sleeve body 106 has a plurality of combinations of filamentcross-section geometries at the intersection points, the plurality ofcombinations of filament cross-section geometries forming a plurality ofprotuberance thicknesses, a thickness of each protuberance beingmeasured in a radial direction of the sleeve body. In a second statewhen a fastener is inserted into the tubular lattice, pressure from thefastener 102 can be transmitted to the tubular lattice such that thespatial relationship of the protuberances changes according to afunction of bone density and according to a function of an interfacingsurface shape of the fastener.

The woven retention device 100 can thus be configured to impede biofilmformation. The biomaterial of the woven retention device 100 can be madeof a material that impedes biofilm formation. The sleeve body can have astructure that impedes biofilm formation.

The retention device 100 can thus be configured to promote boneingrowth. The biomaterial of the woven retention device 100 can be madeof a material that promotes bone formation. The sleeve body can have astructure that promotes bone ingrowth.

The sleeve body can be configured to receive a portion of the softtissue and the sleeve body is configured to impede biofilm formationsurrounding the soft tissue. The sleeve body comprises a coating on theplurality of filaments, wherein the coating comprises an orthopedicbiomaterial. The plurality of filaments can comprise the orthopedicbiomaterial.

Referring now to the figures, FIG. 1C shows a woven sleeve or patch 200in an exploded state outside of the bone placement for interfacing witha bone surface, according to an example of an embodiment. The patch 200,as shown, may have a general configuration or construction in the formof a patch shown as a sleeve body 206 including a plurality ofinterwoven filaments that may form a lattice. The general configurationof the lattice can be flat and adapted to accommodate a typical shape ofa bone, for example. The woven patch can have a degree of elasticity(ability to return to the woven patch to return to the original/natureshape) or flexibility to adapt to various bone structures. The wovenpatch can be elastically formed into various sizes by the translation ofthe woven or braided fibers that does change the interstices sizes whileadapting to various bone structures. Additionally, variousconfigurations of the sleeve body 206 can be contemplated in accordancewith the principles of the invention.

The lattice may include a plurality of protuberances distributed on afirst surface, or an interior surface, and a second surface, or anexterior surface, of the lattice at a predetermined spatialrelationship. Each of the plurality of protuberances may be formed by anintersection of filaments. More particularly, each of the plurality ofprotuberances may be formed by an intersection point of two or more ofthe plurality of interwoven filaments. The intersection can be referredto as a location and/or point. Additionally, the interwoven filamentsmay outline interstices that allow for bone ingrowth. The woven patchcan also have a proximal end that is proximal to the sleeve body 206 andthat is configured to be applied to at least a portion of a fastener(not depicted). The woven patch 200 can also have a distal end that isdistal to the sleeve body 206. In some embodiments, the distal end isformed to ease insertion of the woven patch 200. For example, the distalend in FIG. 1C is tapered or closed. The lattice can be a tubularlattice.

The woven patch 200 can be applied to a bone and interact with both thebone and a screw. While the woven patch 200 can achieve an interferencefit functionality by providing additional interference in between afastener and the bone, in some embodiments, the woven patch can insteadof and/or in addition to function as a woven patch in accordance withthe configurations, functions and advantages that are discussed herein.For example, the woven patch can have a dual interface between a radialscrew surface on one side and multiple points of contact on a bonesurface on the other side. The dual interfaces on the patch areconfigured to be adapted to the bony structure on the outside and thescrew on the inside, as described herein in accordance with theprinciples of the invention. The woven patch can be particularlybeneficial for osteoporotic or weakened bone that has more space gapsthan normal bone to allow additional points of contact for the interfaceto contact. The woven patch 200 may any of those described in co-pendingapplication Ser. Nos. 15/359,021, 15/374,773 and 14/569,542, hereinincorporated by reference. It may be appreciated that the functions andproperties of the woven retention device 100 describe herein may alsoapply to the woven patch 200.

As discussed in detail further below, the plurality of interwovenfilaments may include one or more varieties of filament shapes and sizessuch that the sleeve body 106 can have a plurality of combinations offilament cross-section geometries at the intersection of the filaments,which can also be referred to as intersection points of the filaments.Because each intersection of the filaments may form a protuberance, theplurality of combinations of filament cross-section geometries may forma plurality of protuberance thicknesses, each thickness being measuredin a radial direction of the sleeve body 106. For example, across-section geometry can include a shape of the cross-section and/or asize of the cross-section. The combination of the filament cross-sectiongeometries can include the cross-section geometries of both filaments atthe intersection. The combination of filament cross-section geometriescan form a plurality of interstices sizes and shapes to promote boneingrowth.

The spatial relationship of the plurality of protuberances and theplurality of interstices can also change as a function of loading and/orthe fastener. The spatial relationship of the plurality of protuberancesand apertures can change as a function of an interfacing surface shapeof the fastener 102. In one embodiment, where the screw has a largerpitch, for instance in a larger size of screw, the retention device wheninterfacing with the screw can change to accommodate the coarse threads.For example, the retention device can adapt to follow the crests and thevalleys to create a general wave pattern. On the other hand, in the caseof a smaller diameter screw, or a finer thread with smaller pitch, theretention device can deform or bend over the peaks of the threads less.Thus, in one embodiment, the absolute value of pullout resistance can begreater with a larger screw but the delta between the differential canbe smaller with the larger diameter screw because of additionalinterwinding of the intermediary point of contact. That is, in oneembodiment, the protuberances on the exterior surface do not interfaceas much with the bone because of some of the protuberances foldinginward because of the coarseness of the thread. Whereas on the smalldiameter screw, the woven retention device can move more uniformly,which can allow for greater interdigitation. Thus, because there can beless chance for those interdigitation points to reach into the valleysof the threads, there is more interaction with the bony surface. Thegreater interaction on the bony surface also enhances and increases theamount of contact of the interstices to the bone surface to promote boneingrowth.

The spatial relationship of the plurality of protuberances and theplurality of interstices can also change as a function of an interfacingsurface shape based on the length of the surface. For example, thesurface of the fastener 102 can also be various lengths. Even though thechange in pullout resistance can be greater with large screws than smallscrews in total pullout resistance, the small screw can have greaterpullout resistance as a measure of percent change. One factor thataffects the small screw having a greater pullout resistance in percentchange is that more interaction with the woven retention device 100 canbe possible with a smaller fastener as a percentage of the fastener'spercentage of coverage. This can result in a larger differential in pullout resistance in the smaller sizes than there is in the larger sizesbecause of the increased interaction. In one embodiment, the mechanicalproperties of the woven retention device can compensate for differencesin the fastener surface. For example, to increase bone surfaceinteraction with a fastener 102 that has a coarse thread, a wovenretention device with a greater level of stability can be used toprevent the filaments from retreating too far into the valleys andinstead interacting with the bone surface.

In some embodiments, the woven retention device 100 may be specificallyconfigured for a bone of a particular density or range of densities. Forexample, the structural configuration, material properties, or otheraspects of the woven retention device may be adjusted to provide desiredengagement with the bone surface of a particular density or range ofdensities. However, in some embodiments, a particular woven retentiondevice may be suitable for use in bones of varying densities.

FIG. 2 shows the woven retention device 1008 with a tapered distal end116 along its longitudinal axis. The tapered distal end 116 may taper toa distal tip 115 that has a smaller diameter than the sleeve body 106.The woven retention device 1008 may be the same or similar to the wovenretention device 100.

FIG. 3 shows a close-up view of the woven retention device 1008 of FIG.2 , according to one embodiment. As explained below, a set of filamentscan include one or more filaments. In one embodiment, a set of filamentscan include filaments that are side by side and the filaments includingan inner filament and an outer filament. The inner filament in oneembodiment can be disposed on the left of the outer filament, as viewedfacing the receiving portion in a longitudinal direction. For example,FIG. 3 shows one embodiment of a woven retention device 1008, whereineach of the first plurality of sets of filaments 120 includes a firstinner filament 126 and a first outer filament 128, and each of thesecond plurality of sets of filaments 122 includes a second innerfilament 132 and a second outer filament 130. In one embodiment, one ofthe outer filaments and the inner filaments can be a round monofilament140 and one of the outer filaments and the inner filaments can be a flatmultifilament 142. However, in another embodiment, filament 142 can be around monofilament with a different or a same diameter as monofilament140. In one embodiment, the woven retention device 1008 is configuredsuch that the plurality of interwoven filaments are comprised ofalternating round monofilaments and flat multifilaments. In thisembodiment, each of the sets of filaments can have a consistent anduniform order of filaments, which allows for a uniform arrangement ofprotuberances. In another embodiment, the plurality of interwovenfilaments are comprised of alternating round monofilaments of a firstdiameter and round filaments of a second diameter that is greater thanor less than the first diameter.

As shown in FIG. 3 , in one embodiment, the first inner filament 126 canbe a flat multifilament 142, the first outer filament 128 can be a roundmonofilament 140, the second inner filament 132 can be a flatmultifilament 142 and the second outer filament 130 can be a roundmonofilament 140. However, it may be appreciated that differentmonofilament/multifilament arrangements may be employed.

Each of the different monofilament/multifilament arrangements allow forthe protuberances to occur at different regions. In FIG. 3 , theprotuberances form a diamond arrangement shown by the shape defined byintersection points 144′, 145′, 146′, and 147′.

Each of the different monofilament/multifilament arrangements allow forinterstices to occur at different regions. In FIG. 3 the intersticesform a diamond arrangement by the shape defined by the space captured byintersection points 144′, 145′, 146′, and 147′.

As can be seen from FIG. 3 , the woven retention device 1008 can beconfigured so that the plurality of interwoven filaments follow atwo-under/two-over configuration, where each of the filaments overlietwo intersecting filaments and underlie two intersecting filaments. Inanother embodiment, at each intersection point, a round monofilamenteither overlies both of the intersecting filaments or is overlain byboth of the intersecting filaments and the flat multifilament overliesone of the intersecting filaments and is overlain by the other of theintersecting filaments. However, other contemplated embodiments includea one-over-one weave provided that there is sufficient rigidity andflexibility of the filaments to generate the protuberances.

For FIG. 3 , alternative weaving patterns besides the two-over/two-underconfiguration are also contemplated within the broad inventiveprinciples disclosed herein. A one-over/one-under configuration iscontemplated where each filament alternatingly overlies and underlies anintersecting filament. In one embodiment, a three-over/three-under weavepattern is contemplated where each filament overlies three intersectingfilaments before underlying three intersecting filaments. In anotherembodiment, a two-over/one-under is contemplated where each filamentoverlies two intersecting filaments and then underlies one intersectingfilament. Alternatively, a one-over/two-under arrangement is alsopossible where a filament overlies one intersecting filament beforeunderlying two intersecting filaments. In another embodiment, athree-over/one-under is contemplated where each filament overlies threeintersecting filaments and then underlies one intersecting filament.Alternatively, a one-over/three-under arrangement is also possible wherea filament overlies one intersecting filament before underlying threeintersecting filaments. With each of these weaving patterns, sufficientstability, rigidity, compressibility, sheer strength, and/or tensilestrength can allow for the pressure from the fastener is able totransmit force in a distributed manner to the bone surface.

The round monofilaments of the woven retention device can have differingdiameters. In one embodiment, the round monofilaments can have adiameter in a range of about 0.1 mm 0.4 mm. In one embodiment, the roundmonofilament of the woven retention device is 0.2 mm. In anotherembodiment, the round monofilaments can have alternating monofilamentsof different diameters.

The multifilaments of the woven retention device according to someembodiments can have various thicknesses and widths. For example, amultifilament may have a thickness of less than 0.1 mm. Thecross-sectional shape, e.g., flat or round, and the texture, forexample, of the multifilaments can also be relevant. The number offilaments and pattern can also be relevant. As such, with thoseconsiderations, various filament linear mass densities can becontemplated. For example, the multifilaments can have a linear massdensity in a range of about 150-250 denier. In one embodiment, themultifilaments can have a linear mass density of about 200 denier.

The woven retention device can be configured such that the intersectingsets of filaments form a plurality of differently shaped and differentlysized apertures or pores. In one embodiment, as shown in FIG. 3 , thefirst inner and outer filaments of one set of first filaments can begrouped closer to each other than the other sets of first filaments.Likewise, the second inner and outer filaments of one set of secondfilaments can be grouped closer to each other than the other sets ofsecond filaments. When the two sets of filaments intersect, as shown inFIG. 3 , the area which is outlined by the first and second plurality ofsets of filaments is a plurality of differently shaped and differentlysized apertures 148. By having differently shaped and sized apertures, amore conducive environment for non-uniform bony surface can allow foringrowth of bone to occur. Additionally, improved interdigitation withthe bony structure can be achieved with a combination of the aperturesand protuberances.

In one embodiment, the intersecting sets of filaments createparallelograms of open space or pores 148 (see FIG. 11 ). The pores 148have a pore size defined by a diagonal corner to corner length. That is,the pore size is defined by the 3-dimensional distance between fibersurfaces. For example, for the parallelogram pores shown in FIG. 11 ,the pore size can be described as the length between opposing diagonalcorners. In an exemplary embodiment, the pore size may be in apredetermined range of 200-1000 μm. That is, the minimum pore size is200 μm (e.g. a minimum 3-dimensional linear distance between fibers) andthe maximum pore size is 1000 μm (e.g. a maximum 3-dimentional lineardistance between fibers).

In an exemplary embodiment, the average pore size is about 600 μm. In anexemplary embodiment, the average pore size is about 600 μm+/−200 μm. Inan exemplary embodiment, the average pore size is about 600 μm+/−400 μm.In an exemplary embodiment, the minimum pore size is about 400 μm andthe maximum pore size is about 800 μm. In an exemplary embodiment, theminimum pore size is about 400 μm and the maximum pore size is about 600μm. In an exemplary embodiment, the minimum pore size is about 600 μmand the maximum pore size is about 800 μm. In an exemplary embodiment,the minimum pore size is about 200 μm and the maximum pore size is about1000 μm. In an exemplary embodiment, the minimum pore size is about 200μm and the maximum pore size is about 600 μm. In an exemplaryembodiment, the minimum pore size is about 600 μm and the maximum poresize is about 1000 μm. In exemplary embodiment, the minimum pore size isabout 100 μm and the maximum pore size is about 1100 μm. Although thepore size has been described in relation to the 3-dimensional distancebetween fibers, it may be appreciated that pore size may be measured inother manners. For example, the pores may be defined as a volume ofspace between the fibers. The pore size may thus be defined as thedistance from the geometric center of the volume of space to any fiber.

As may be appreciated, since the pore size is defined by the fiberspacing, the pore size may also be defined by the braiding parameters,as will be discussed in more detail below. That is, the under/overarrangement and location of the different fiber sizes (e.g. alternatingspools of 0.2 mm and 0.3 mm fiber on the bobbins located on thecircumference of the spindle) on the bobbins, the picks per inch, andthe braid angle. The natural compression and expansion diameter range ofthe woven retention device may be defined by the braiding parameters, asdescribed in Tables 1-3.

The following parameters define the large (6.5 mm) size:

TABLE 1 Exemplary braiding parameters for large woven retention device.Counter Clockwise Bobbins Clockwise Bobbins Size # of Size # of Size #of Size # of (mm) Carriers (mm) Carriers (mm) carriers (mm) Carriers 0.212 0.3 12 0.2 12 0.3 12

-   -   Pattern: 3 0.3 mm fibers for every 1 0.2 mm fibers, producing a        2-over, 2-under pattern    -   Braid angle: 40-45 degrees    -   Pick count: 25 picks per inch

In exemplary embodiments, the braid angle may be 35-50 degrees. Inexemplary embodiments, the pick count may be 20-35 picks per inch.

The following parameters define the small (2.0 mm) size:

TABLE 2 Exemplary braiding parameters for small woven retention device.Counter Clockwise Bobbins Clockwise Bobbins Size # of Size # of Size #of Size # of (mm) Carriers (mm) Carriers (mm) carriers (mm) Carriers 0.212 0.3 12 0.2 12 0.3 12

-   -   Pattern: 1 0.2 mm fiber for every 1 0.1 mm fiber, producing a        2-over, 2-under pattern    -   Braid angle: 40-45 degrees    -   Pick count: 45 picks per inch

In exemplary embodiments, the braid angle may be 35-50 degrees. Inexemplary embodiments, the pick count may be 35-35 picks per inch.

The following parameters define the medium (3.5 mm) size:

TABLE 3 Exemplary braiding parameters for medium woven retention device.Counter Clockwise Bobbins Clockwise Bobbins Size # of Size # of Size #of Size # of (mm) Carriers (mm) Carriers (mm) carriers (mm) Carriers 0.112 0.2 12 0.1 12 0.2 12

-   -   Pattern: 1 0.2 mm fiber for every 1 0.1 mm fiber, producing a        2-over, 2-under pattern    -   Braid angle: 40-45 degrees    -   Pick count: 47 picks per inch

In exemplary embodiments, the braid angle may be 35-50 degrees. Inexemplary embodiments, the pick count may be 37-57 picks per inch.

It has been demonstrated that bone desires a certain pore size topromote growth. The woven retention device may be compressed into a bonehole and then expanded by a screw (such as fastener 102) as the screw isinserted into the woven retention device. The pores 148 of the wovenretention device stay within a pore size range that is optimal for bonegrowth. The pores 148 remain in the pore size range regardless if thediameter of the woven retention device is compressed or expanded toensure bone growth can occur regardless of the bone hole size in whichit is inserted. As discussed above, the pore size predetermined rangemay be 200-1000 μm. The compression or expansion of the woven retentiondevice is accomplished by the translation of the fibers with respect toeach other, which in turn decreases or increase the pore size. Thus, thepore size may be different for different woven retention devicediameters but within the optimal range for bone ingrowth.

In embodiments, the woven retention device size, e.g. the diameter ofthe woven retention device is determined for a bone hole size where acertain amount of fiber translation and uniform diameter change mayoccur without altering the circular cross-sectional shape of the wovenretention device and provide the optimal engagement of the protuberanceswith the bone.

It may be appreciated that the woven retention device for each size(e.g. small, medium, large, XL) was selected so the pore size rangeremained the same for each woven retention device size. If the braidingparameters are held constant for each size and the overall diameter ofthe woven retention device was increased, the pore size would bealtered. FIGS. 12 a, 12 b, and 12 c show the same woven retention devicescaled up in diameter, all in the relaxed position. The fiber coverage(density) decreases as the pore size increases as the diameter isincreased.

A 3-dimensional distance may be the distance between two points in3-dimensional space, that is, where the two points are not in the sameplane. For example, in the case of a parallelepiped, such as is providedin the woven retention devices of FIGS. 12 a-12 c , the four corners ofone face of the parallelepiped may be labeled A, B, C, and D. The3-dimensional distance may be the distance between points A and C, forexample. Due to the curvature of the woven retention devices, thesepoints may not lie in the same plane, and as such, the distance betweenthe points may be thought of as a 3-dimensional distance. The3-dimensional distance may define the pore size. The pore size mayremain within the predetermined range regardless of the diameter of thewoven retention device. Thus, it may be appreciated that the pore sizeis the same in each of FIGS. 12 a, 12 b , 12 c.

The braiding parameters were modified for each woven retention devicesize to maintain the same fiber volume and pore size. The small, medium,and large woven retention device are formed with the same fiber volumeand same pore size by varying the fiber size, number of fibers (e.g.number of bobbins), pick count, and/or braid angle, or any combinationthereof. Each woven retention device size is unique with respect to thebraiding parameters. Each woven retention device pore geometry may bedefined by the braiding parameters. Referring to Table 4, the totalnumber of fibers is 48 for the large woven retention device, 48 for themedium woven retention device, and 24 for the small woven retentiondevice. For example, referring back to Table 1, the large wovenretention device may have 12 fibers of 0.2 mm diameter from the counterclockwise bobbins, 12 fibers of 0.3 mm diameter form the counterclockwise bobbins, 12 fibers of 0.2 mm diameter from the clockwisebobbins, and 12 fibers of 0.3 mm diameter from the clockwise bobbins,for a total of 48 fibers. In another exemplary embodiment, the mediumwoven retention device geometry is further defined by the 2 under/2-overpattern, the location of the different fiber sizes (e.g. alternatingspools of 0.2 mm and 0.3 mm fiber on the bobbins located on thecircumference of the spindle) on the bobbins, the chosen 29 picks perinch, and the 45° braid angle.

TABLE 4 Exemplary fiber diameters and fiber numbers for different wovenretention devices Small Medium Large Size of Fibers 0.2 & 0.1 mm 0.2 &0.1 mm 0.3 & 0.2 mm No. of Fibers 24 48 48

The interwoven filaments of a woven retention device extend around thetubular lattice in an angle range. In one embodiment, the angle canrepresent a range from about 40-60 degrees with respect to alongitudinal direction of the woven retention device. In anotherembodiment, the angle can represent a range from about 15-75 degreeswith respect to a longitudinal direction of the body sleeve. In oneembodiment, the angle represents 45 degrees. The retention device can,in the relaxed state, have the interwoven filaments that extend aroundthe tubular lattice at about a 45 degree angle with respect to alongitudinal direction of the woven retention device.

According to another embodiment, the braid angle can be smaller than 45degrees. According to another embodiment, when the woven retentiondevice has an average diameter of 2 mm, the braid angle can be about 35degrees.

An exemplary method of braiding a woven retention device, such as wovenretention devices 100 and 1008, will be described. The fibers orfilaments may be spooled on bobbins in a circumference and rotated in a“maypole” pattern together to create the cylindrical braid. Thefibers/filaments converge on a mandrel to create a cylindrically shapedbraid. The bobbins placed along a large circumference. Each bobbincontains a spool of fiber/filaments. The fibers/filaments converge tothe center of the large spindle to create the braided cylinder. Thebraiding process may be the one shown and described in co-pendingapplication Ser. Nos. 14/569,541 and 15/374,773, herein incorporated byreference.

The pore shape is illustrated as a 2-dimensional parallelogram in theside longitudinal view of the woven retention device (FIG. 11 ). Theactual 3 dimensional shape is a parallelepiped that creates aparallelogram-shaped aperture for bone to grow into and through.

The braiding pattern creates a varying 3-dimensional pore size and shapethat creates a complex asymmetrical network of pores. The pores vary insize, shape and orientation on the braided sleeve, as illustrated inFIG. 11 Although the pores appear to be 2-dimensional (e.g.parallelograms), the cylindrical braid pattern actually forms3-dimensional shapes (e.g. parallelepiped apertures) that are orientatedin multiple directions. The 3-dimensinal shapes or volumes formed by thefibers create “tunnels” (e.g. empty spaces) for bone to growth into inall directions through the sleeve. For example, bone is able to growradially through a pore towards the center longitudinal axis of thesleeve, around the circumference of the sleeve, or tangentially from theouter circumference of the sleeve through the sleeve thickness and thenoutward through the thickness at another location on the circumference.The boundaries of the parallelepiped open space/volumes are created bycylindrical monofilament fiber surfaces. The monofilament fibers formthe boundaries by crossing under and over each other. Since thefibers/filaments can translate with respect to each other and are notfused together along their lengths, there are small gaps between themalong their length. Bone is not blocked from growing into and throughthese spaces. Therefore, there are always 3 directions for which bone toform, creating a complex 3 dimensional network of bone cells that canconnect in all directions at each pore.

The pores create a complex 3-dimensional interface with the bonecomplementary to the varying protuberance thickness that creates acomplex mechanical interface with the bone. The pore interface is not amechanical transfer of load as the protuberance is, but a space intowhich bone can respond. That is, the protuberances are created by thefibers and directly touch the bone. The pores also touch the bone whenthe bone is permitted to grow into the pores. By optimizing the poresize (through optimizing the braid pattern), the woven retention deviceachieves both the protuberances for transferring of load and the poresto promote optimal bone growth. Alternating protuberances createalternating pores for bone growth. For example, the diagram of FIG. 13illustrates the varying sized protuberances in 1 direction, and theassociated varying sized pores adjacent to them. FIG. 13 is a schematicwhich represents the cross-section of the device, cut-away into theopening. The protuberances actually vary in 3 dimensions and similarlythe pores vary in 3 dimensions as well.

The protuberances vary in thickness and shape, interdigitating with thetrabeculae of the bone hole, as disclosed in co-pending application Ser.Nos. 15/359,021 and 14/569,542, herein incorporated by reference.Similarly, there is intimate contact of the pore with bone, facilitatingbone growth from the bone hole through the pore for varying bonedensities.

In one embodiment, the woven retention device can have a length in arange of about 30 mm to 150 mm. The length of the woven retention devicecan come in dynamically cuttable; and/or predetermined length, such assmall—30 mm; medium—40 mm, large—40 mm, and other sizes (or ranges) arealso possible. In one embodiment, the woven retention device can have adiameter of about 1.5 mm to 10.0 mm. The diameter of the woven retentiondevice can come in predetermined sizes, such as (i) small: 2.0 mm fine(can accommodate 1.3 mm to a little over 2.0 mm pilot hole diameter andcan fit 2.0 mm-2.7 mm screws); (ii) medium: 3.5 mm-6.0 mm course (canaccommodate 2.4 mm to a little over 3.2 mm pilot hole diameters and canfit 3.5-6 mm screws); and (iii) large: 6.5 mm-9 mm very course (canaccommodate 4.1 mm to a little over 5.9 mm pilot hole diameters and canfit 6.5-9.0 mm screws).

In a relaxed state, the woven patch can be of various lengths anddiameters. In one embodiment, the woven patch can have a length in arange of about 10 mm to 150 mm. In an embodiment, the woven patch canhave a length in a range of about 30 mm to 60 mm. The length of thewoven patch can come in dynamically cuttable; and/or predeterminedlength, such as small—30 mm; medium—40 mm, large—40 mm, and other sizes(or ranges) are also possible.

The sleeve can work at filling the hole better to provide more points ofcontact for the bone interface. One way it can do so is by having twosleeves nested, which can add additional advantages using the multiplepoints of contact interface. It can also have a homogeneous and uniforminterface for screw engagement so that a number of characteristics ofthe sleeve can be achieved: Rigidity, Compressibility, Stability, Sheerstrength (at a predetermined level), Tensile strength (at apredetermined level). The implantable retention device can be made of atleast one of silk, non-woven felt, and collagen.

Various methods of using the woven retention device can be used. FIG. 4details steps that can be performed in conjunction with the wovenretention device. The woven retention device may be inserted into a bonehole alone and then a fastener can be inserted. Alternatively, the wovenretention device and screw can we combined prior to insertion and thecombination inserted into the bone hole. The invention is not limited tothe steps described in FIG. 4 , is not limited to the order of the stepsdisclosed, and does not require that certain of the disclosed steps beperformed.

In one embodiment, in step S400, a bone can be drilled to form a bonehole.

In one embodiment, the woven retention device can be elongated orconstricted in step S402, after which in step S404 the woven retentiondevice can be inserted into the bone hole. After step S404, in step S406the woven retention device upon entering the bone hole can be expanded.Thus, upon entering the bone hole, the woven retention device can expandto a less elongated and constricted state to interface with the bonesurface. After step S406, in step S408 the fastener can be inserted intothe woven retention device either before or after insertion into thebone hole. Next, the fastener can exert pressure on an interior of thewoven retention device in step S410. In step S410, the fastener canoptionally change the shape of the interior of the woven retentiondevice. Next, in step S412, pressure from an interior of the wovenretention device can be distributed to an exterior surface of the wovenretention device. In step S412, the shape of the exterior surface of thewoven retention device can optionally change shape. In step S414,pressure from an exterior surface of the woven retention device cantransmit to bone surface. In step S414, the pressure transmission to thebone surface can optionally change the shape of the bone surface. Inother embodiments, the steps can be performed in different orders orsteps can be optionally omitted.

In another embodiment, instead of following steps S402, S404, S406 andS408, in step S401, a fastener can be inserted into the woven retentiondevice before the woven retention device has been inserted into the bonehole, after which in step S403 the fastener with woven retention devicecan be inserted into the bone hole. After step S403, in step S410 thefastener can optionally change the shape of the interior of the wovenretention device. Next, in step S412, pressure from an interior of thewoven retention device can be distributed to an exterior surface of thewoven retention device. In step S412, the shape of the exterior surfaceof the woven retention device can optionally change shape. In step S414,pressure from an exterior surface of the woven retention device cantransmit to bone surface. In step S414, the pressure transmission to thebone surface can optionally change the shape of the bone surface.

FIG. 5 shows a graph of examples of pullout strengths of a screw incontrol bone hole, a screw in a stripped bone hole, and, according to anexample of an embodiment of the invention, a screw in a woven retentiondevice in a stripped bone hole. A stripped bone hole is one in which ascrew, for one reason or another, has lost purchase or fit. For example,the bone may degrade or break to the point that the fit between the boneand the screw is lost, or part of the structure of the bone may bestripped or sheared by the screw itself, for example. As can be seenfrom FIG. 5 , a screw in a stripped bone hole can cause a decrease AS inthe pullout strength of the screw as compared to a control screw that isin a bone hole that is not stripped. In addition, the woven retentiondevice in accordance with the principles of the invention can cause anincrease AW in the force required to pullout the screw as compared tothe screw by itself in a stripped hole. Although not shown in FIG. 5 ,the woven retention device can increase the pullout strength of thescrew beyond that of a screw in a non-stripped hole, such as the controlscrew, including in cases where the woven retention device is used inconjunction with a screw in a non-stripped hole.

FIG. 6 shows a graph showing examples of different pullout forcesbetween small screws in various different pilot holes. As can be seenfrom FIG. 6 , the combination of the screw and woven fixation device, inaccordance with the principles of the invention, has more pullout forcein each of the tested sizes.

FIG. 7 shows a graph showing examples of different pullout forcesbetween medium screws in various different pilot holes. As can be seenfrom FIG. 7 , the combination of the screw and woven fixation device, inaccordance with the principles of the invention, has more pullout forcein each of the tested sizes.

FIG. 8 shows a graph showing examples of different pullout forcesbetween large screws in various different pilot holes. As can be seenfrom FIG. 8 , the combination of the screw and woven fixation device, inaccordance with the principles of the invention, has more pullout forcein each of the tested sizes.

FIG. 15 shows an exemplary spine ovine study showing bone growth over 12weeks with a 4.5 mm screw.

According to embodiments of the invention, the woven retention devicecan enhance pullout force percentage compared with a screw alone for arange of hole diameters. However, the woven retention device used with asmall screw may allow for a higher percentage increase of pullout forcethan with medium and large screws. For example, the woven retentiondevice according to an embodiment has been shown to add at least a 10%increase in pullout strength compared with the pullout force of a screwwithout a woven retention device. Specifically, for small holediameters, the increase has been shown to be 33% to 77%, according to anexample of one embodiment. For medium hole diameters, the increase hasbeen shown to be 10% to 72%, according to another example of anembodiment. Finally, for large hole diameters, the increase has beenshown to be 12% to 30% according to another example of an embodiment.

Examples of woven retention devices according to embodiments werefabricated using different combinations of filaments. Table 5 showsdetails of the five versions of these examples. Each version includestwo types of counter clockwise filaments, and two types of clockwisefilaments. “Type” refers to whether the filament is mono-filament ormulti-filament. “Size” indicates the diameter (measured in millimeters)of the monofilaments, and the linear mass density (measured in decitex,or dtex, which is grams per 10,000 meters) for the multifilament. “# ofCarriers” refers to the number of each filament. Version 1 is acombination of mono- and multifilaments. Version 2 is onlymonofilaments, where the monofilaments are all the same size. Version 3is a combination of two different sizes of monofilaments. Version 4 is acombination of three different sizes of monofilaments. The wovenretention devices in Versions 1-5 each had a braid angle of about 40° to45°, and were sized to accommodate screw with an inner core diameter ofabout 6.5 mm (corresponding to the “large” size discussed above). Thefilaments were made of polyethylene terephthalate (PET).

TABLE 5 Examples of woven retention devices used for measuring pulloutstrength Counter Clockwise Filaments Clockwise Filaments # of # of TypeSize Carriers Type Size Carriers Version 1 mono 0.2 mm 12 mono 0.2 mm 12multi flat 196 12 multi flat 196 12 dtex dtex Version 2 mono 0.2 mm 12mono 0.2 mm 12 mono 0.2 mm 12 mono 0.2 mm 12 Version 3 mono 0.2 mm 12mono 0.2 mm 12 mono 0.1 mm 12 mono 0.1 mm 12 Version 4 mono 0.4 mm 12mono 0.2 mm 12 mono 0.1 mm 12 mono 0.1 mm 12 Version 5 mono 0.2 mm 12mono 0.2 12 mono 0.3 mm 12 mono 0.3 12

FIGS. 9 and 10 show the results of axial pullout strength using Versions1-5 of the woven retention device in Table 5 as compared to the pulloutstrength of a screw without a woven retention device. Both tests usedpilot holes with a diameter of 4.1 mm in polyurethane foam, and a screwwith an inner core diameter of 6.5 mm and length of 40 mm. In the testsof FIG. 9 , 15 pcf rigid polyurethane foam was used. In the tests ofFIG. 10 , 10 pcf rigid polyurethane foam was used. For all tests, theaxial pullout strength was greater when a woven retention device wasused, compared to when a screw was used without a woven retentiondevice. Furthermore, FIGS. 9 and 10 show that the greatest pulloutstrength in these tests was achieved for Version 2, which comprised onlymonofilaments of the same size. Also, the percentage increase comparedto screw-only pullout was greater in the less dense (10 pcf)polyurethane foam, indicating that embodiments of the present inventionmay well suited for lower density bone, such as osteoporotic orosteopenic bone, for example.

There is a need for devices, systems and methods that enhance thesurface of a bone hole to provide enhanced fixation of a bone anchor tothe bone such as is described in copending application Ser. No.15/374,773, herein incorporated by reference. Additionally, there is aneed for devices, systems and methods for repairing the surface of thebone hole following damage to the bone hole as in the case of strippingof the hole in the bone when a bone screw is over-tightened. Also, thereis a need for devices, systems and methods for providing an enhancedbone hole surface for the reattachment of tendons in, for exampleanterior/posterior cruciate ligament repair procedures, rotator cuffrepair procedures, etc. There is a need for a device that enhances thesurface of a bone hole to enhance fixation of a bone anchor to bone andpermits bone ingrowth into its structure. There is a need for a singledevice that enhances the surface of a bone hole to enhance fixation of abone anchor to bone and accommodates variations in the diameter anddepth of the bone hole. Further, there is a need for such devices thathave enhanced biocompatibility to aid in tissue and bone healing,regeneration, and growth.

According to an embodiment of the present invention, a retention devicefor interfacing with a bone surface and promoting bone ingrowth andimpeding biofilm development is provided. The retention device includesa sleeve body including a plurality of filaments forming a substantiallytubular lattice with a plurality of protuberances distributed on aninterior surface and an exterior surface of the tubular lattice at apredetermined spatial relationship. The sleeve body can surround atleast a portion of a fastener, and each of the plurality ofprotuberances may be formed by an intersection point of two or more ofthe plurality of filaments that outline a plurality of apertures. Thefilaments can include an orthopedic biomaterial. The retention devicealso may include a proximal end that is proximal to the sleeve body andthat can receive at least a portion of the fastener, and a distal endthat is distal to the sleeve body. In a first state, the sleeve body mayhave a plurality of combinations of filament cross-section geometries atthe intersection points, the plurality of combinations of filamentcross-section geometries forming a plurality of protuberancethicknesses. A thickness of each protuberance is measured in a radialdirection of the sleeve body. In a second state when a fastener isinserted into the tubular lattice, pressure from the fastener can betransmitted to the tubular lattice such that the spatial relationship ofthe protuberances changes according to a function of bone density andaccording to a function of an interfacing surface shape of the fastener.

In an aspect of an embodiment, the retention device can be a wovenretention device and the filaments may be interwoven. The orthopedicbiomaterial can include a hydrophilic material that attracts bonegrowth, and the hydrophilic material can be a metal. The orthopedicbiomaterial can include non-resorbable polymer fibers. The orthopedicbiomaterial can include at least one of osteostimulative, antimicrobial,and plasma-rich-platelet (PRP) agents applied to the filaments. In anembodiment, the non-resorbable polymer fibers are roughened to wick oneof osteostimulative, antimicrobial and plasma-rich-platelet agents. Theorthopedic biomaterial may include biologic fibers that are configuredto absorb into a body, and the non-resorbable polymer fiber and thebiologic fibers may be interwoven.

As may be appreciated from the foregoing disclosure, the fundamentalrequirement for bone growth is the linear distance between obstacles. Inthe case of a woven retention device, the linear distance is thefilament to filament distance, and in particular, the diagonal distanceof the 3-dimensional shape (e.g. a parallelepiped). The preferred rangefor the linear distance between filaments surfaces is greater than 200μm and smaller than 1000 μm for every pore. This range may be extendedto 100 μm to 1100 μm. The target distance may be 600 μm. However, notevery pore has to be optimally sized for bone growth since having smallgaps that do not allow bone to grow will not adversely impact fixationmeasurably. Fixation would depend on the surface area covered with bone.For example, if the number of pores that prevent bone growth is lessthan 10% of the area then the fixation strength would not be affected.

As may further be appreciated, having a pore size which promotes boneformation may impede biofilm formation. Biofilm formation is stimulatedby an adverse reaction to a material, like a foreign body response orgrowth of infection from influx of bacteria etc. Where there is boneformation, there is nothing else, and thus biofilm formation may beimpeded. However, there could be normal soft tissue growth instead ofbiofilm. Normal soft tissue (fibrotic response) can fill in the emptyspace if there is no promotion of bone growth (e.g. the gap is verylarge and there is no stress or micromotion to stimulate the bone torespond). Less normal soft tissue growth occurs with the interwovenretention device of the present disclosure since it bridges the gap,transfers load to the bone to stimulate growth, and provides a platformto grow onto.

Furthermore, when the pores are constricted and/or expanded, the poresize still falls within the predetermined range. The shape of the pore(e.g. the parallelepiped) may change, but the overall distance betweenfilaments remains in the predetermined range. The area of the aperturemay change dynamically by interwoven filaments translating with respectto each other without substantial stretching of the interwovenfilaments. If one constricts or expands the sleeve, first there istranslation of fibers then eventually there is stretching or buckling ofthe fibers. The constricted aperture areas may change by a function of abraid of the filaments. The aperture area (shape of the parallelograms)at rest is determined by the braid. Therefore, the shape of the apertureafter compression or expansion is also determined by braid. Aspreviously discussed, the pore size may be defined in other terms andmay be the area, length, width, or other dimension of the pore. Any ofthese parameters may define the pore size since what impacts bone growthis the 3-dimensional distance between surfaces (obstacles) that wouldprevent growth. If the 3-dimensional distance is too small, theosteoclasts are impeded from creating bone and if the 3-dimensionaldistance is too large, the osteoclasts are not constrained and will notform bone. The braid parameters that create the protuberances forincreased fixation can also create a pore size for optimal bone growth.The braid of the sleeve that creates asymmetrical protuberances for 3-Dinterdigitation for fixation also create asymmetrical pores for 3-Doptimal bone growth. The pore size may stay in a range that is optimalfor bone growth regardless of the diameter of the sleeve when compressedor expanded.

The embodiments illustrated and discussed in this specification areintended only to teach those skilled in the art the best way known tothe inventors to make and use the invention. Nothing in thisspecification should be considered as limiting the scope of the presentinvention. All examples presented are representative and non-limiting.The above-described embodiments of the invention may be modified orvaried, without departing from the invention, as appreciated by thoseskilled in the art in light of the above teachings. It is therefore tobe understood that, within the scope of the claims and theirequivalents, the invention may be practiced otherwise than asspecifically described.

What is claimed is:
 1. A woven retention device to promote bone ingrowthand impede biofilm formation, the woven retention device comprising: asleeve body comprising a plurality of interwoven filaments; a proximalend that is proximal to the sleeve body and that is configured toreceive a fastener; and a distal end that is distal to the sleeve bodyon an opposing side of the proximal end, wherein in a relaxed state ofthe woven retention device, the interwoven filaments outline pores, eachof the pores having a pore size along a plane of the tubular lattice,each pore size within a range of 200-1000 μm, wherein in a constrictedstate of the woven retention device, the pore size changes as a functionof a diameter of the sleeve body, the pore size remaining within therange of 200-1000 μm, and wherein the pores are configured to promotebone ingrowth.
 2. The woven retention device of claim 1, wherein an areaof the pores changes dynamically by interwoven filaments translatingwith respect to each other without substantial deforming of theinterwoven filaments.
 3. The woven retention device of claim 2, whereinthe area of the pores changes by a function of a braid of the filaments.4. The woven retention device of claim 3, wherein the pore size isdefined along a long axis or a major axis of the sleeve body.
 5. Thewoven retention device of claim 4, wherein the interwoven filamentsdefine a plurality of protuberances distributed on an interior surfaceand an exterior surface of the tubular lattice at a predeterminedspatial relationship.
 6. The woven retention device of claim 5, whereinin the relaxed state each pore is shaped as one of a diamond, arectangle, a square, or a parallelogram.
 7. A woven retention device topromote bone growth, the woven retention device comprising: a sleevebody comprising a plurality of interwoven filaments that form asubstantially tubular lattice having a plurality of pores having apredetermined pore size, the plurality of pores defined by a pluralityof adjacent filaments of the plurality of interwoven filaments, whereinthe woven retention device is configured to move between a relaxed stateand a constricted state, wherein the pore size falls within apredetermined range and remains substantially within the predeterminedrange when the woven retention device is in the relaxed state and theconstricted state, and wherein the pore size promotes bone growth in thepores.
 8. The woven retention device of claim 7, wherein the pore sizeis defined by a 3-dimensional distance between surfaces of the pluralityof adjacent filaments.
 9. The woven retention device of claim 7, whereinthe pores define a parallelepiped between the plurality of adjacentfilaments.
 10. The woven retention device of claim 7, wherein the3-dimensional distance between surfaces of the plurality of adjacentfilaments is a length between opposing diagonal corners of the pores.11. The woven retention device of claim 7, wherein the pore size iswithin the range of 200 μm and 1000 μm.
 12. The woven retention deviceof claim 7, wherein the pore size is about 600 μm.
 13. The wovenretention device of claim 7, wherein the pore size is defined when thewoven retention device is in the relaxed state.
 14. The woven retentiondevice of claim 7, further comprising a plurality of protuberancesdistributed on an interior surface and an exterior surface of thetubular lattice at a predetermined spatial relationship.
 15. The wovenretention device of claim 7, wherein the pore size is defined along along axis or a major axis of the sleeve body.
 16. The woven retentiondevice of claim 7, wherein the pore size remains in the range of 200 μmand 1000 μm when a diameter of the sleeve body changes.
 17. A kit,comprising: a first woven retention device having a first diameter, thefirst woven retention device having a first sleeve body comprising afirst plurality of interwoven filaments that form a substantiallytubular lattice having a plurality of first pores; and a second wovenretention device having a second diameter, the second woven retentiondevice having a second sleeve body comprising a second plurality ofinterwoven filaments that form a substantially tubular lattice having aplurality of second pores, wherein the second diameter is greater thanthe first diameter, and wherein the first pores and the second poreshave substantially the same pore size, and wherein the pore size iswithin the range of 200 μm and 1000 μm.
 18. The kit of claim 17, whereinthe woven retention device is configured to move between a relaxed stateand a constricted state, and wherein the pore size remains substantiallywithin the range when the woven retention device is in the relaxed stateand the constricted state.
 19. The kit of claim 18, further comprising athird woven retention device having a third diameter, the third wovenretention device having a third sleeve body comprising a third pluralityof interwoven filaments that form a substantially tubular lattice havinga plurality of third pores, wherein, the third diameter is greater thanthe second diameter, and wherein a pore size of the third pores issubstantially the same as the pore size of the first pores and the poresize of the second pores.
 20. The kit of claim 19, wherein the firstpores, the second pores, and the third pores are all defined by a3-dimensional distance between surfaces of adjacent interwoven filamentsof the respective plurality of interwoven filaments.